The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
An aircraft is driven by several turbojet engines each accommodated in a nacelle also harboring a set of ancillary actuation devices related to its operation and ensuring various functions when the turbojet engine is operating or at a standstill. These ancillary actuation devices notably comprise a mechanical system for actuating a thrust reverser.
A nacelle generally has a tubular structure along a longitudinal axis comprising an air intake upstream from the turbojet engine, a middle section intended to surround a fan of the turbojet engine, a downstream section harboring thrust reversal means and intended to surround the combustion chamber of the turbojet engine. The tubular structure generally ends with an ejection nozzle, the outlet of which is located downstream from the turbojet engine.
Modern nacelles are intended to harbor a dual flux turbojet engine capable of generating via rotating blades of the fan a hot air flow (also called a “primary flow”) stemming from the combustion chamber of a turbojet engine, and a cold air flow (“secondary flow”) which circulates outside the turbojet engine through a ring-shaped passage also called an “annular vein”.
By the term of “downstream” is meant the direction corresponding to the direction of the cold air flow penetrating the turbojet engine. The term of “upstream” designates the opposite direction.
The annular vein is formed in the downstream section by an external structure called an outer fixed structure (OFS) and an internal concentric structure called an inner fixed structure (IFS) surrounding the structure of the engine strictly speaking downstream from the fan. The internal and external structures belong to the downstream section. The external structure may include one or several rotationally mobile doors so as to be capable, under the action of driving means, of switching between an inactive closed position during the operation of the turbojet engine, a so called “direct thrust” mode, in which the doors form a portion of the downstream section, and a reversal position or open position in which they switch so that a downstream portion of each door will at least partly obturate the conduit of the nacelle and an upstream portion in the downstream section opens a passage allowing the airflow to be radially channeled relatively to a longitudinal axis of the nacelle.
In order to be able to improve the reorientation of the air flow in a direction tending as close as possible towards a longitudinal direction of the nacelle, some doors have been equipped with terminal spoilers, also called baffles, forming upstream from the door a return element substantially perpendicular to the plane formed by the latter. Thus, when the door is in the thrust reversal position, the spoiler is orientated in a direction substantially longitudinal to the nacelle and forces the air flow in this direction.
When the door is in the closed position, each spoiler is orientated along a direction substantially perpendicular to the longitudinal axis of the nacelle and penetrates the air flow circulation vein. There is the risk that the spoiler will then block the air flow circulating in the direct thrust mode, which is not permissible.
In order to overcome this drawback, doors have been designed so as to have an upstream cavity at an internal surface of said door. Consequently, the door has reduced thickness upstream which allows both the spoiler to protrude from said door and not to have a length greater than the thickness of the nacelle upstream from the door in order not to penetrate the annular circulation vein of the air flow when the door is in the closed position.
However, such a cavity forms a significant aerodynamic hindrance inside the annular air flow vein when the door is in the closed position, which reduces the overall performances of the turbojet engine.
Rotationally mobile spoilers along a plane perpendicular to the plane of the door, called a “deflection plane”, are known from application FR 2916484.
In spite of the advantages provided by the operation of such spoilers, it may prove to be of interest to increase the front surface area of each spoiler in contact with the deflected air flow in order to improve the orientation of the whole of the deflected air flow.